I am installing a 3/4 bath in my basement. It will include a toilet, sink, and shower. They will all be tied into an ejector sewage pit. Do I have to vent each fixture? Also, what is the proper way to secure the PVC drain pipes below the concrete? Will back filling with gravel underneath the pipes be sufficient or I saw a diagram that showed the pipes being secured by vertical pieces of wood with plastic straps. Any advice will be appreciated. Thanks.